Growing Asparagus

Enlarge Image Image Gallery Plant once, harvest for years: A well-maintained bed of this sweet, slender veggie will stay productive for up to 15 years, and, with its vibrant, ferny foliage, asparagus makes an excellent ornamental. Shown here, from left to right, are ‘Jersey Giant,’ ‘Purple Passion’ and fronds of a mature asparagus plant. ILLUSTRATION: KEITH WARD

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Gardeners have been growing asparagus (Asparagus officinalis) for more than 2,000 years, and this sweet, slender veggie’s staying power is no surprise: A well-maintained asparagus bed will start bearing one year after planting and will stay productive for 10 to 15 years.

A hardy perennial adapted in Zones 3 to 8, asparagus grows best in well-drained soil with a near-neutral pH between 6.5 and 7.5. The edible part of the asparagus plant is the young stem shoot, which emerges as soil temperatures rise above 50 degrees Fahrenheit in spring.

Types to Try

Because asparagus stays productive for so long, it’s important to plant the best variety available for your area. In cold climates, ‘Guelph Millennium’ and other varieties that emerge late often escape damage from spring freezes. In warm climates, early, heat-tolerant varieties such as ‘Apollo’ and ‘UC-157’ produce well before the weather turns hot. Gardeners in Zones 4 to 6 have a wider selection of varieties, including ‘Jersey Giant,’ ‘Jersey Knight’ and other hybrids bred in New Jersey for improved disease resistance and better productivity.

When to Plant

Plant asparagus crowns (dormant roots of 1-year-old plants) in spring at about the same time you would plant potatoes, but don’t rush to plant them if your soil is still cold. A few varieties, such as open-pollinated ‘Purple Passion’ and hybrid ‘Sweet Purple,’ can be grown from seed. Start seeds indoors in spring and set out the seedlings when they are 12 to 14 weeks old, just after your last spring frost. Start with asparagus crowns, however, to eliminate the year of tedious weeding that comes with starting from seed.

How to Plant

Choose a site with fertile soil that’s clear of perennial weeds and grasses. A single row of asparagus plants set 15 inches apart will fill in to form a 24- inch-wide bed, or you can grow a double row in a 36-inch-wide bed. Locate asparagus along the back or side of your garden, as 5-foot-tall asparagus fronds will shade any nearby plants. A bed of 25 mature plants will produce about 10 pounds of asparagus per year.

Asparagus craves phosphorus, which is usually abundant in composted manure and in compost made from kitchen waste. Add a 2-inch layer of rich, weed-free compost to your soil before planting. Dig a trench 4 inches deep and 10 inches wide in the amended soil and arrange the crowns in the bottom, about 15 inches apart. Refill the trench without stepping on the bed.

Maintaining Your Bed

Controlling weeds during the first two seasons will require rigorous weeding by hand. Pull out weeds early and often, and mulch with hay, grass clippings or another organic material to suppress weeds and maintain moisture. Weeds will become less of an issue as the plants fill in.

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